title: Novel fundamental building blocks and site dependent isomorphism in the first actinide borophosphates.
abstract: Three novel uranyl borophosphates, Ag2(NH4)3[(UO2)2{B3O(PO4)4(PO4H)2}]H2O (AgNBPU-1), Ag(2-x)(NH4)3[(UO2)2{B2P5O(20-x)(OH)x}] (x = 1.26) (AgNBPU-2), and Ag(2-x)(NH4)3[(UO2)2{B2P(5-y)AsyO(20-x)(OH)x}] (x = 1.43, y = 2.24) (AgNBPU-3), have been prepared by the H3BO3-NH4H2PO4/NH4H2AsO4 flux method. The structure of AgNBPU-1 has an unprecedented fundamental building block (FBB), composed of three BO4 and six PO4 tetrahedra which can be written as 9□:[Φ] □<3□>□|□<3□>□|□<3□>□|. Two Ag atoms are linearly coordinated; the coordination of a third one is T-shaped. AgNBPU-2 and AgNBPU-3 are isostructural and possess a FBB of two BO4 and five TO4 (T = P, As) tetrahedra (7□:□<4□>□|□). AgNBPU-3 is a solid solution with some PO4 tetrahedra of the AgNBPU-2 end-member being substituted by AsO4. Only two out of the three independent P positions are partially occupied by As, resulting in site dependent isomorphism. The three compounds represent the first actinide borophosphates.
authors.affiliation: Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 511 Kehua Street, 510640 Guangzhou, P. R. China.
authors.forename: Shijun
authors.initials: S
authors.lastname: Wu
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Polinski
authors.forename: Thomas
authors.initials: T
authors.lastname: Malcherek
authors.forename: Ulrich
authors.initials: U
authors.lastname: Bismayer
authors.forename: Martina
authors.initials: M
authors.lastname: Klinkenberg
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Modolo
authors.forename: Dirk
authors.initials: D
authors.lastname: Bosbach
authors.forename: Wulf
authors.initials: W
authors.lastname: Depmeier
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Albrecht-Schmitt
authors.forename: Evgeny V
authors.initials: EV
authors.lastname: Alekseev